The field of the invention relates to a calibration system for combustion sensors.
Within the combustion section in a gas turbine, a violent combustion process occurs that generates combustion gases that drive the turbine. Extreme temperatures and pressures occur during combustion as compressed air and fuel mix together and combust. The temperatures and pressures in the combustion chamber can fluctuate rapidly and vary over extreme ranges.
Monitoring the combustion reaction is helpful in controlling the fuel flow to the combustor and the operating mode of the gas turbine. To monitor the combustion reaction, temperature and pressure sensors are placed within the combustion and turbine sections of a gas turbine. These sensors monitor the combustion process and the combustion gases. The sensors generate signals that are indicative of the temperature or pressure of the combustion gases. The signals from the sensors are used by the computer controller for the gas turbine to set the operational conditions for the gas turbine, including fuel flow and compressor inlet vane positions. In addition, the sensor measurements are used to ensure that the temperatures and pressures within the combustor and turbine sections, do not exceed threshold pressure and temperature conditions.
To ensure that accurate pressure and temperature measurements are made, the sensors within the combustion section and turbine section should be properly calibrated so that they provide accurate measurements of temperature and pressure. It is generally desirable to calibrate and test temperature and pressure sensors under conditions comparable to those in which the sensors are intended to operate. Sensors in the combustion section of a gas turbine operate in conditions of extreme temperature and pressure, and should accurately measure rapid fluctuations in pressure. There is a long-felt need to calibrate sensors in conditions which replicate those in the combustor of a gas turbine. Similarly, there is a long-felt need for calibration systems for combustor sensors that replicate the temperature and pressure conditions in the combustor section of a gas turbine.
In one embodiment, the invention is a pressure sensor calibration system comprising a pressure chamber in fluid communication with a pressure sensor to be calibrated, the chamber is pressurized to a static pressure level. An oscillating surface on a wall of the chamber imparts a rapid pressure fluctuation in the static pressure level of the chamber. These rapid pressure fluctuations in a high-static pressure level chamber are used to calibrate the pressure sensor. The calibration system may be used to calibrate dynamic sensors at gas turbine working conditions, such as static pressures greater than 200 psi (14 kilo/mm) and temperatures greater than 700xc2x0 F. (370xc2x0 C.).
In a second embodiment, the invention is pressure sensor calibration system comprising a probe holder having a mount for a pressure sensor to be calibrated, wherein the holder has an aperture in fluid communication with a pressure generator, and the pressure generator has a pressure chamber coupled to a steady source of high pressure gas to pressurize the chamber to a static pressure level. The pressure chamber also has an oscillating surface which dynamically varies the static pressure level in the chamber, and the oscillating surface is oscillated by a shaker device.